Revision 0:f401474a3e96, committed 2010-10-27

Comitter:

nimbusgb

Date:

Wed Oct 27 15:27:38 2010 +0000

Child:

1:20aa2d4a28bf

Commit message:

0.8

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sht75.cpp	Wed Oct 27 15:27:38 2010 +0000
@@ -0,0 +1,180 @@
+//
+// Ian Molesworth October 2010
+// SHT 75 class
+//
+// 
+// To do:
+//
+// 
+
+#include "sht75.h"
+
+void SHT75::reset()
+    {
+     _data.output();
+    _data = 1;                                        // data bus high
+    for (int i=0;i<12;i++)
+        {
+        _clock = 1;                                   // clock high
+        wait_us(1);
+        _clock = 0;                                   // clock lo
+        wait_us(1);
+        }
+    _clock = 1;                                   // clock high
+        wait_us(1);
+    _data  = 0;
+        wait_us(1);
+    _clock = 0;                                   // clock lo
+        wait_us(1);
+    _clock = 1;
+        wait_us(1);
+    _data  = 1;
+        wait_us(1);
+    _clock = 0;   
+        wait_us(1);
+    }
+
+void  SHT75::softReset(void)
+    {
+    _data.output();
+    start();
+    write(0x1E);
+    wait_ms(12);
+    }
+
+void  SHT75::start(void)
+    {
+    _data.output();
+    _clock = 1;
+    wait_us(1);
+    _data = 0;
+    wait_us(1);
+    _clock = 0;
+    wait_us(1);
+    _clock = 1;
+    wait_us(1);
+    _data = 1;
+    wait_us(1);
+    _clock = 0;
+    }
+
+int SHT75::readStatus(void)
+    {
+    int status;
+    status = -1;
+    start();
+    if (write(0x06) == 0)
+        status = read(1);               // read with a wait for ack
+    read(0);                            // read without the wait
+    return status;
+    }
+
+bool SHT75::write(char d)
+    {
+    auto int i;
+    _data.output();                         // bus output
+    // Writes char and returns -1 if no ACK was sent from remote
+    for (i=0;i<8;i++)
+        {
+        if (d & 0x80)
+            _data = 1;                      // data high
+        else
+            _data = 0;                      // data lo
+        // shift the data
+        d <<= 1;
+        wait_us(1);
+        _clock = 1;                         // clock high
+        wait_us(1);
+        _clock = 0;                         // clock lo
+        }
+    _data.input();                          // float the bus
+    wait_us(1);
+    _clock = 1;                             // clock high
+    wait_us(1);
+    i = _data;
+    _clock = 0;                             // clock lo
+    return i;                               // leave the bus in input mode and return the status of the ack bit read.
+    }
+
+int SHT75::read(char ack)
+    {
+    auto int i,s;
+    auto char c;
+    s = 0;
+    _data.input();                            // bus to input
+  
+    for (i=0;i<8;i++)
+        {
+        s <<= 1;
+        wait_us(1);
+        _clock = 1;                              // clock high
+        wait_us(1);
+        c = _data;                               // get the data bit
+        _clock = 0;                             // clock lo
+        if ( c )
+            s |= 1;
+        }
+
+    if (ack == 1)
+        _data = 0;                             // data lo
+    else
+        _data = 1;                             // data hi
+    _data.output();
+    _clock = 1;                                // clock lo
+    wait_us(1);
+    _clock = 0;                              // clock lo
+    _data = 1;                               // data hi
+    _data.input();
+    return s;
+    }
+
+
+// Put the current temperature into passed variable
+bool SHT75::readTempTicks(int* temp)
+{
+  int v, value;
+  start();                                  // Start a tx ( leaves data as input )
+  if (write(0x03) == 0)                     // send the read command and get an ack
+        {
+        for (v=0; v<50; v ++)               // wait for ready up to 500 ms
+            {
+            wait_ms(10);                    // 10 ms pause
+            if ( _data == 0 )               //
+                {
+                value = read(1);            // read a byte
+                value <<= 8;                // shift it in
+                value |= read(1);           // read another byte
+                read(0);
+                // transfer the value
+                 *temp = value;
+                reset();
+                return true;
+                }
+            }
+        }
+    return false;    
+    }
+
+bool SHT75::readHumidityTicks(int* humi)
+    {
+    start();
+    if (write(0x05) == 0)
+        {
+        for (int value=0; value<50; value ++)   // wait for ready up to 500 ms
+            {
+            wait_ms(10);                        //
+            if ( _data == 0 )                   //
+                {
+                value = read(1);
+                value <<= 8;
+                value |= read(1);
+                read(0);
+                *humi = value;                  // transfer the value
+                reset();
+                return true;
+                }
+            }
+        }
+   
+    return false;
+    }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sht75.h	Wed Oct 27 15:27:38 2010 +0000
@@ -0,0 +1,75 @@
+/* mbed Sensiron SHT7x temperature and humidity sensor library
+*
+* Sensiron data at http://www.sensirion.com/en/01_humidity_sensors/06_humidity_sensor_sht75.htm
+*
+* Copyright (c) Ian Molesworth October 2010
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to use
+* copy or modify the software for private or non-commercial purposes only. 
+*
+* The above copyright notice and this permission notice shall be included in
+* all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+* THE SOFTWARE.
+*/
+
+
+#ifndef SHT75_H
+#define SHT75_H
+
+#include "mbed.h"
+
+const float C1= -4.0;              // for 12 Bit humi
+const float C2= +0.0405;           // for 12 Bit humi
+const float C3= -0.0000028;        // for 12 Bit hum
+const float TL= -39.61;             // 3v 14 bit 
+const float T1= +0.01;             // for 14 Bit @ 5V
+const float T2= +0.00008;          // for 14 Bit @ 5V
+
+class SHT75 
+    {
+    public:
+     /** Create an SHT object connected to the specified Digital pins
+      *
+      * @param pclock digital pin to use as clock
+      * @param pdata digital pin to use as data bus ( bidirectional ) 
+      */
+        SHT75(PinName pclock, PinName pdata): _clock(pclock), _data(pdata) {};
+     /** read the temperature ticks value 14 bit resolution
+      *
+      * @param int *temp pointer to an integer to hold the tick value
+      * @returns boolean true if read acknowledges
+      */
+        bool readTempTicks(int* temp);
+     /** read the humidity ticks value 12 bit resolution
+      *
+      * @param int *temp pointer to an integer to hold the tick value
+      * @returns boolean true if read acknowledges
+      */
+        bool readHumidityTicks(int* temp);
+     /** start up reset
+      *
+      * call to resync or abort current operation.
+      * worth calling every now and then to make sure your system is not hung.
+      */
+        void reset(void);
+        void softReset(void);
+        int  readStatus(void);
+  
+    private:  
+        DigitalInOut _data;
+        DigitalOut _clock;
+        
+        void start(void);
+        int read(char);
+        bool write(char);
+    };
+
+#endif